Process of engraving



Oct; 10, 1939. M. A. CAMPBELL 2,175,739

rnocnss or suemvme Filed Dec. 14, 1938 2 Sheets-Sheet 1 ATTORNEYS M. A. CAMPBELL ,7

mocn'ss OF ENGRAVING Oct. 10, '1939.

2 Sheets-Sheet 2.

Filed Dec. 14, 1938 lllllluul- INVENTOR. 7%: w/v 'A' (AMPBELL' BY f) TM ATTORNEYS Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE 2,175,139 PROCESS OF ENGRAVING Application December 14, 1938, Serial No. 245,694

4 Claims.

This invention relates broadly to the art of making photo-engraved plates and more specifically to an improved method of producin plates for the printed reproduction of pictures in color. This application is a continuation in part of my copending application, Serial No. 161,099,

filed August 26, 1937 and is directed to the subject matter disclosed therein.

The primary object of the invention resides in the use of a series of proof sheets or prints comprising outline replicas of the original drawing and the treatment of such prints to facilitate the production of the color plates.

The invention further contemplates a method in which the arduous and costly work entailed in the exercise of the Ben Day process is eliminated, and a method of making plates with sharper definition of outline and greater depth of tone than has been realized by the methods heretofore employed.

In the production of photo-engraved plates for certain types of color work, it is the custom to prepare one plate in delineation of the composition and an additional plate for each color v impression desired in the reproduction of the original picture. Each color plate is formed with type high areas for the transcription of a particular color, while the portions of the plate which register with areas where other primary colors occur are etched or routed below type level. The shaded tones and infusion of color are, in certain classes of printing, obtained by exercise of the Ben Day process which is too well known by those skilled in the art to justify description herein. I

' In the practice of'the method constituting-the present invention proof sheets, (one for the prep-.

aration of each color plate) are printed from the outline plate, the materials from which these proofs or work prints are made and the subsequent treatment thereof being of such a character as to produce an effect which is comparable to the appearance of work produced by the Ben Day process, thus one of the most costly operations in the preparation of the plates may be eliminated. In addition, further economies may be realized in the exercise of the improved method since the work of the retouch artists, and that of the engraver and router may be executed with greater expedition, and with results superior to those possible in the. practice of the ni'ethods heretofore employed.

Referring to the drawings, which exemplify but one of the types of printing in which the improved method may be used, and which is shown only for the purpose of illustration:

Figure 1 is a reproduction of an artists sketch of a portion of a newspaper comic strip which, it will be assumed, is rendered in polychromatic treatment;

Figure 2 is a proof sheet or work print of the outline plate made from the drawing of Figure 1;

Figure 3 is the work print of Figure 2 prepared for the production of the yellow color plate;

Figure 4 is a similar work print prepared for m the production of the blue plate of the color plate series;

Figure 5 is a similar workprint prepared for the production of the red plate; Figure 6 illustrates the appearance of a proof made from the yellow plate of Figure 3 showing the loss of certain lineation and showing diagrammatically the tone contrasts produced by the treatment of the work prints;

Figure 7 illustrates a proof made from .the blue plate of Figure 4 showing the appearance thereof and the variable tone values attained in the production of the plate;

Figure 8 illustrates the proof made from the red plate of Figure 5 showing the various shades of color effectuated by the treatment of the work print therefor; and

Figure 9 is an illustration of the finished color print made by printing the yellow, red, blue and outline plates in superposed relation, the colors herein being shown in the conventional diagrammatic manner.

In the exercise of the method constituting the present invention the artists drawing or picture I0 is first reproduced by the usual photo-engraying method to produce a key plate showing only the outline of the subjects comprising the composition. From this plate proof sheets or work prints II are printed, preferably on a relatively heavy cardboard which is suitably colored to show a vivid contrast with pure whitewhen certain portions of the drawing are painted out by the retouch artist.

The color of the cardboard is preferably of a photographic value at least 25% darker than white, but when the predominating tone of the artist's copy is dark a drawing board of a darker shade may be used and lighter opaque washes may be applied to develop the shaded contrast.

It has been found that a but! or deep tan will provide sufllcient latitude for the application of an opaque paint which though lighter than'the field of the board will still produce the desired con- 5 2 trast with white and also contrast with the darker opaque washes.

In printing the outline upon the carboard work print II, a colored ink is used, the color being one of the group which is unsusceptible of photographic reproduction, or a color which may be blocked photographically by the use of filters and/or a suitable sensitizing material. For example, a pale, blue ink may be used which will clearly show the lineation l2 of the design upon the work print, but which, in the absence of photographic color correction, will fail to develop in a negative made of the work print. Thus as illustrated in Figure 3, the lines l2 remaining in the print after application of the opaque washes will not be photographically reproduced in a. negative made therefrom nor in the etched plate made from such negative as will be recognized by reference to the proof copy of the color plate thereof shown in Figure 6.

As shown herein for the purpose of illustration the color plate impression set comprises plates for yellow, blue and red. In the preparation of the yellow plate the artist first selects one of the work prints II and applies a wash of India ink or similar black opaque material upon the portions it of the print in which the strongest tone of yellow occurs in the original drawing. The printed outline on the work print provides a guide for blocking in the area so treated and facilitates the execution of this operation with accuracy and dispatch. The artist next applies a wash of pure white paintupontheareas which aretobe made opaque in the negative and etched out in the plate in order to preserve a field in which other colorsare tobeprintedor afieldwhichwillremain unprinted in the final reproduction.

Aswillbeseeninfiguredwhichillustratesa proof printed from the plate made from the work print ll, shown in Figure 3, the opaqued portions ll of the drawing are reproduced with a relatively strong yellow field. the areas ll coated with whltepaint and etched or undercut in the plate are reproduced as white herein or to show the field Ila of the paper stock empl e while the unpainted portions 01 the work print where the normal color of the stock remains. are reproduced in a lighter shade of yellow llain contrast withtheareas II. It willbe notedthat the uncoated outline l2 in the work print does not appear in the p The blue plate is prepared in a similar manner, the artist selecting a second work print ll, pplying India ink thereon to block in the areas It (Fig. 4) which form the blue impreslon field in the plate, next coating with white paint the portions IQ of the work sheet which are to be etched below the printing surface, then applying a wash ll of a light opaque material upon the areas which are of the next lighter tone of blue in the original drawing.

Thus as will be seen in Figure 7, (a proofof the plate made from the work print of Figure 4) the area [1a, which is the transcription of the light opaque wash II appears lighter in tone than the areas Iia painted black. but of a deeper shade of blue than the areas I! of the normal color of the cardboard or work print I I.

Preparation of the red plate is similar to that of theyellow and blue plates, the artist taking the third printed work print ll applying India ink upon the areas It with white paint where in etching it is desired to bite plate, applying a modified or light opaque sash 2|.upon.the'areas where it is desire I to pro-- (Fig. 5), coating the areas 20 duce a pale red shade and painting with an opaque wash 22 of a deeper shade the areas which appear in the original drawing to darker shade of red than the areas 2| lighter tone than the areas Ill.

be of a still but a As will be seen in Figure 8, the proof made from the red plate, the reproduced color board or work print ll appears as a of the cardpink area 23,

the second deeper tone 2i of red appears in the zone where the wash 2| was deeper tone 25 of red appears of red appears in applied, a third in the area where fourth tone 26 which were painted with India ink or similar opaque material.

proofs, Figures 7 and 8, as well It will be noted that in the as the proof shown inFigure 6, the outline i2 which was printed in colored ink on the work print I l was not reproduced when the work sheets graphed for After the touched as heretofore the preparation oi the etched plates. work prints ii are painted or redescribed they are photowere photographed through a half tone screen which is ruled to produce the this operation desired size or form of dots. In each work print is photographed at a different angle, for example. the first print may be revolved through an angle of the second through an angle of while the third print is turned through an angle of in order to obtain the oifset relation of the dots copy. Moreover,

is so timed as to overexpose the in the printed the exposure in this operation areas painted in solid, opaque white so that the screen dots will be entirely eliminated and sharp contrast or delineation of color area boundaries will be obtained without routing or tooling the etched plates made from the negatives graphed.

thus photo- In standard practice when a white background is used and the photographic exposure therefor is timed to eliminate generally the field or background screen dots, minute points or microscopic dots will be found fringin the perimeter of heavy dot shade areas. invention, however, are eliminated as an In the practice of such points or minute dots exposure which will elimithe present nate background screen dots in the colored background of the work sheets, areas painted in opaque white and feet a sharp and clear lineation of of the shade areas or zones in the work contrast. Thus when prepared for sharp color will overexpose the completely efthe boundaries sheets the negative is printed on metal for etching, the borders of the impression areas or marginal edges of the portions which have been painted with opaque white will be defined by boundaries so sharp, clear and definite as to eliminate the neces- "2 after sity of routing or retouch engraving of the plate the etching operation. The photographic then printed on sensitized metal plates and etched in the usual manner. In printing, the finished color print illustrated in Figure 9, impressions are posed relation, work prints Ii being line i2a as shown painted areas on the various in Figure 9.

made in superthe outline or key plate for the run in black to form the out- Obviously the plates will register accurately with each other and with the lineation I2a since all of the retouch work was executed from the printed outline I2 on each of the work prints II.

From the the opaque accuracy and expedition than has been possible heretofore since each of the work prints is print.

ed from the key plate and therefore of identical outline, and since the paper from which the work prints are made can be chosen from stock which.

will facilitate a smooth, even application of paint. Moreover, the washes, particularly that of white paint, may be applied with suiiicient density and accuracy of tracery to produce a negative that is absolutely opaque in the areas so treated and in turn an etching of sharp definition and uniform depth. It will be further recognized that when the work prints 1 l are photographed through the screen the variable tones of the opaque washes will be broken into dots proportional in size to the density of the wash and will thus produce tones of variated shade which in appearance is comparable to the work produced by the method in which the screen rulings vary for different shade areas. Although reference has been made in the foregoing to the use of opaque washes, it is to be understood that crayon, pastel or similar materials may be substituted therefor and that shading for graduation of tone may be effectuated by such medium.

It will be further understood that theinvention is not to be construed as restricted specifically to the foregoing disclosure nor to the terminology employed herein for the materials used in the practice of the improved method. The invention in its broader aspect comprehends the method of preparing work sheets for color plate production from a material of any color other than white, then coating with an opaque compo-- sition which is darker than the field of said material the areas therein which are to be reproduced as the respective color plates and also coating with an opaque composition which is substantially lighter than the field of said material the areas therein which are to be etched below printing level of the respective color plates. After the work sheets are thus prepared the photographic reproduction thereof is timed as though the colored field of the work sheets were white so that the areas treated with the light, opaque composition will be overexposed and produce an etched surface in the eliminate the necessity of routingabout the boundaries of the coated areas. When reflection is given the mode of application'of the opaque composition the advantage of the uniform printed outline on the respective work sheets will be apparent. With an outline before him, which may be photographically eliminated. the workman need only paint with sharp line tracing the areas which are to be reproduced or etched below type level.

One of the uses to which the foregoing method has been adapted with commercial and economic success is that of reproducing newspaper comic strips theretofore produced by the Ben Day method. Obviously, however, the method constituting the present invention is not limited to such field of endeavor.

Although reference has been made in the foregoing to the elimination of the Ben Day process by use of the method disclosed herein, it is to be understood that the two methods may be employed conjointly; that is certain areas of a drawing may be treated by the Ben Day process while the remaining areas are treated in the manner disclosed above. It will be recognized that substantial economy of reproduction may be realizedevenwhenthe two methods are thus employed,

I claim: 4

1. The method of making photo-engraved color plate of suflicient depth to plates which comprises, making an etched plate of an outline drawing of the picture to be reproduced, printing therefrom a work sheet for each color plate to be made, said work sheets being formed of a colored paper which is darker than white and approximately the shade of the lightest color tone in said picture, painting in black the areas in the respective work sheets where full color tone is to be produced in the color plates to be made therefrom, painting in opaque white, in sharp line detail about the printed outline, the areas in the respective work sheets where sharp line color contrast occurs in said picture, photographing each work sheet through a half tone screen in a manner which will eliminate the printed outline and in a manner which will eliminate the screen dots in the areas painted in opaque white, then making etched plates from the negatives of the work sheets thus photographed. v

2. The method of making photo-engraved color plates which comprises, making an etched plate of an outline drawing of the subject picture, printing with a colored ink, a work sheet for each color plate to be made, said work sheets being formed of a colored paper which is approximately twenty-five percent darker than white and approximately the shade of the lightest tonein the subcorrespond to the portions of the subject picture where sharp color contrast occurs,..the opaque white paint being applied to form sharp line definition about the areas so painted, photographing each work sheet through screen and in such a manner as to eliminate the color printed outline on said work sheets, the photographic exposure being timed to overexpose the areas painted in white, then making etched plates from the negatives of the work sheets thus photographed.

3. The method of making photo-engraved color plates which comprises, making an etched plate of an outline drawing of the picture to be reproduced, printing, with blue ink, work sheets from said plate, said work sheets being formed of a colored paper which is approximately twentyfive percent darker than white and approximately the shade of the lightest tone in said picture, painting in solid opaque black the areas in each work sheet where the deepest color is to be produced in the color plate to be made therefrom, the outline on thework sheet constituting the guide therefor, painting in solid opaque white the areas in each work sheet where the half tone screen dots are to be eliminated in the color plate to be made therefrom, the outline in the work sheet constituting the guide therefor, photographing each work sheet so painted through a half tone screen and in such a manner as to eliminate the printed blue outline from said etched plate, the exposure therefor being timed to overexpose the areas painted in white, then making etched plates from the negatives of the work sheets thus photographed.

4. The method of making photo-engraved color plates, which comprises making a photo-engraved plate of a line drawing of the picture to be reproduced, printing therefrom with blue ink, a work sheet for each color plate to be made, said work sheets being formed of a colored paper which is approximately the shade of the lighest tone in said picture and approximately twenty-five percent darker than white, painting in solid opaque black the areas in the work sheets where full color value is to be produced in the respective color plates, the painted outline on the work sheet forming the guide therefor, painting in solid opaque white, the areas in the work sheets where sharp lineation of color contrast is to be produced in the reproduction of said picture, the printed outline on the work sheets forming the guide therefor, painting certain other portions of the work sheets with an opaque material of shades lighter than the unpainted portions of the work sheets and certain other portions of the work sheets with an opaque material of shades darker than the unpainted portions of the work sheets, the printed outline on the work sheets forming the guide therefor, photographing each work sheet through a half tone screen in a manner which will eliminate the blue printed outline and eliminate the screen dots by overexposure of the areas painted in solid opaque white, then making 10 etched plates from the negative of the work sheets thus photographed.

' MELVIN A. CAMPBELL. 

